This invention relates generally to metal frame and glass structures and more particularly to a new glazing system for such structures.
Tempered glass door and sidelight structures have recently enjoyed an increase in popularity and use, particularly in office and other commercial buildings. The popularity of such structures is primarily due to the enhanced aesthetic effect they offer over the more traditional, non-transparent door and sidelight structures.
Typically, glass door and sidelights are installed in a metal frame and held therein by any one of a variety of adhesives or fixatives. These assemblies, however, require costly set-up and fixtures and require considerable skill to properly set and bond the tempered glass panel in place. Furthermore, these assemblies are particularly disadvantageous when the glass panel and metal frame is to be assembled on-site.
Mechanical-type glazing systems are also known, such as for example, U.S. Pat. No. 4,423,582 to Yates. These mechanical glazing systems typically teach the use of a continuous structure, such as for example a wedge, to apply pressure to the glass panel. The use of a continuous structure, however, presents several disadvantages. For example, a continuous structure attempts to straighten out the natural warp, bow or kink of the glass panel by spanning from high point to high point and trying to level the valley therebetween. As such, the glass panel is subjected to increased stress, thus making the glass panel more susceptible to breakage. Another disadvantage in using a continuous structure is that they tend to concentrate the load on the lower edge of the glass panel due to the distortion of the metal frame when the pressure is applied. This concentration of load, in turn, makes the glass panel more susceptible to breakage.
Still another disadvantage of the known mechanical glazing systems arises when the use of thick glass panels is desired. As the thickness of the glass panel increases, the side walls of the door shoe defining the channel become thinner in order to accomodate the thicker glass. The reduced thickness of the side walls makes the walls more susceptible to bending and breaking. When a 3/4 inch glass panel is used, the side walls of the shoe have become so thin that they will no longer withstand the pressure generated against them by the glazing structure. As such, when thick glass panels are desired, a larger door shoe must be provided, which reduces the overall utility of the system.
I have invented a mechanical glazing system which overcomes the above-mentioned disadvantages of the known glazing systems by providing a plurality of independent expandable pressure units to secure the glass panel within the metal frame whereby an even pressure is exerted on the glass panel to reduce the stress on the glass. The use of independent pressure units is particularly advantageous when thick glass panels are desired, in which case a localized recess can be made in the side wall of the channel to accomodate the panel and the pressure units without the concomitant structural impairment of the door shoe observed in the prior art systems. The present invention is also easier and cheaper to manufacture and assemble than existing glazing systems.